| Message ID | 1448890711-5812-3-git-send-email-daniel.wagner@bmw-carit.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/30/2015 02:38 PM, Daniel Wagner wrote: > With the introduction of the simple wait API we have two very > similar APIs in the kernel. For example wake_up() and swake_up() > is only one character away. Although the compiler will warn > happily the wrong usage it keeps on going an even links the kernel. > Thomas and Peter would rather like to see early missuses reported > as error early on. > > In a first attempt we tried to wrap all swait and wait calls > into a macro which has an compile time type assertion. The result > was pretty ugly and wasn't able to catch all wrong usages. > woken_wake_function(), autoremove_wake_function() and wake_bit_function() > are assigned as function pointers. Wrapping them with a macro around is > not possible. Prefixing them with '_' was also not a real option > because there some users in the kernel which do use them as well. > All in all this attempt looked to intrusive and too ugly. > > An alternative is to turn the pointer type check into an error which > catches wrong type uses. Obviously not only the swait/wait ones. That > isn't a bad thing either. Though for the beginning let's introduce it > as options in the kernel hacking section. The kbuild bot found one problem for allmodconfig. I just send a fix for it ("regmap: Fix leftover from struct reg_default to struct reg_sequence change"). -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Nov 30, 2015 at 04:26:03PM +0100, Daniel Wagner wrote: > On 11/30/2015 02:38 PM, Daniel Wagner wrote: > > With the introduction of the simple wait API we have two very > > similar APIs in the kernel. For example wake_up() and swake_up() > > is only one character away. Although the compiler will warn > > happily the wrong usage it keeps on going an even links the kernel. > > Thomas and Peter would rather like to see early missuses reported > > as error early on. > > > > In a first attempt we tried to wrap all swait and wait calls > > into a macro which has an compile time type assertion. The result > > was pretty ugly and wasn't able to catch all wrong usages. > > woken_wake_function(), autoremove_wake_function() and wake_bit_function() > > are assigned as function pointers. Wrapping them with a macro around is > > not possible. Prefixing them with '_' was also not a real option > > because there some users in the kernel which do use them as well. > > All in all this attempt looked to intrusive and too ugly. > > > > An alternative is to turn the pointer type check into an error which > > catches wrong type uses. Obviously not only the swait/wait ones. That > > isn't a bad thing either. Though for the beginning let's introduce it > > as options in the kernel hacking section. > > The kbuild bot found one problem for allmodconfig. I just send a fix for > it ("regmap: Fix leftover from struct reg_default to struct reg_sequence > change"). This will result in an updated series, correct? Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Paul, On 11/30/2015 06:38 PM, Paul E. McKenney wrote: > On Mon, Nov 30, 2015 at 04:26:03PM +0100, Daniel Wagner wrote: >> On 11/30/2015 02:38 PM, Daniel Wagner wrote: >>> With the introduction of the simple wait API we have two very >>> similar APIs in the kernel. For example wake_up() and swake_up() >>> is only one character away. Although the compiler will warn >>> happily the wrong usage it keeps on going an even links the kernel. >>> Thomas and Peter would rather like to see early missuses reported >>> as error early on. >>> >>> In a first attempt we tried to wrap all swait and wait calls >>> into a macro which has an compile time type assertion. The result >>> was pretty ugly and wasn't able to catch all wrong usages. >>> woken_wake_function(), autoremove_wake_function() and wake_bit_function() >>> are assigned as function pointers. Wrapping them with a macro around is >>> not possible. Prefixing them with '_' was also not a real option >>> because there some users in the kernel which do use them as well. >>> All in all this attempt looked to intrusive and too ugly. >>> >>> An alternative is to turn the pointer type check into an error which >>> catches wrong type uses. Obviously not only the swait/wait ones. That >>> isn't a bad thing either. Though for the beginning let's introduce it >>> as options in the kernel hacking section. >> >> The kbuild bot found one problem for allmodconfig. I just send a fix for >> it ("regmap: Fix leftover from struct reg_default to struct reg_sequence >> change"). > > This will result in an updated series, correct? Not necessarily. This patch just points very verbose the incorrect pointer usage in regmap_register_path() users with allmodconfig. This series itself should be okay (unless I missed something). cheers, daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 30 Nov 2015, Daniel Wagner wrote: > > +ifdef CONFIG_ENABLE_ERR_TYPE_CHECK > +KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types) > +endif I don't see a value for making this configurable. If the compiler supports it, we should use it. It already found a bug, so why would we make that optional? Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index 416660d..8817273 100644 --- a/Makefile +++ b/Makefile @@ -625,6 +625,10 @@ KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \ $(call cc-option,-fno-partial-inlining) endif +ifdef CONFIG_ENABLE_ERR_TYPE_CHECK +KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types) +endif + ifneq ($(CONFIG_FRAME_WARN),0) KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) endif diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index ab76b99..21c0193 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -194,6 +194,13 @@ config ENABLE_MUST_CHECK suppress the "warning: ignoring return value of 'foo', declared with attribute warn_unused_result" messages. +config ENABLE_ERR_TYPE_CHECK + bool "Turn pointer type check into an error" + default n + help + Instead of just warning that a wrong pointer type is used, + bail with a proper compile error. + config FRAME_WARN int "Warn for stack frames larger than (needs gcc 4.4)" range 0 8192
With the introduction of the simple wait API we have two very similar APIs in the kernel. For example wake_up() and swake_up() is only one character away. Although the compiler will warn happily the wrong usage it keeps on going an even links the kernel. Thomas and Peter would rather like to see early missuses reported as error early on. In a first attempt we tried to wrap all swait and wait calls into a macro which has an compile time type assertion. The result was pretty ugly and wasn't able to catch all wrong usages. woken_wake_function(), autoremove_wake_function() and wake_bit_function() are assigned as function pointers. Wrapping them with a macro around is not possible. Prefixing them with '_' was also not a real option because there some users in the kernel which do use them as well. All in all this attempt looked to intrusive and too ugly. An alternative is to turn the pointer type check into an error which catches wrong type uses. Obviously not only the swait/wait ones. That isn't a bad thing either. Though for the beginning let's introduce it as options in the kernel hacking section. Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> --- Makefile | 4 ++++ lib/Kconfig.debug | 7 +++++++ 2 files changed, 11 insertions(+)